Altenaeum gibbosum ( Thiele, 1912 )

Zettler, Michael L. & Bick, Andreas, 2025, Molluscs from a shallow bay of King George Island (Antarctica, South Shetland Islands): An annotated checklist with new distributional records, Zootaxa 5631 (3), pp. 401-450 : 418-420

19. Altenaeum gibbosum ( Thiele, 1912) [ Figs 9K–M ]

Tellimya gibbosa Thiele, 1912: 230 , pl. 18, fig. 12

Material examined. • 4 spms, Stn. 2.

Type locality. Gauss station (Davis Sea) at a depth of 385 m.

Bathymetric distribution. 1–752 m.

Substrate. Soft bottom.

Geographical distribution. ANTARCTICA: Circum-Antarctic. SUBANTARCTICA: -. SCOTIA ARC: South Orkney Islands, South Shetland Islands. SOUTH AMERICA: -.

Remarks. The identification of this species was difficult. Mysella minuscula (Pfeffer, 1886) , a species with nomen dubium status in MolluscaBase, which has been observed loosely in some previous studies for King George Island (e.g. Narchi et al. 2002, Passos & Domaneschi 2006), may belong to this species. However, we came to the conclusion that our species belongs to Altenaeum gibbosum . It has a more backward-orientated umbo, which is also somewhat raised. The shape is more ovoid than roundish. The main teeth of the right valve are very short but prominent. Ultimately, however, a certain uncertainty remains in terms of identification. We found a few specimens in the Fildes Strait at a depth of 70 m.

References. Dell (1990), Narchi et al. (2002), Passos & Domaneschi (2006), Aldea & Troncoso (2010a), Huber (2015), Steger et al. (2023).

Figures

FIGURE 9.A–E:Altenaeum charcoti (E. Lamy, 1906); F–J:Altenaeum narchii (Passos & Domaneschi, 2006); K–M: Altenaeum gibbosum (Thiele, 1912). Unless otherwise indicated, the scale is always 1 mm.